The present invention relates to a method and a device for performing lamination under reduced pressure conditions, and more particularly relates to such a method and such a device for reduced pressure lamination, in which the feeding in and the feeding out of materials to be laminated, such as for example printed circuit boards and light sensitive material in film form to be adhered thereto, are performed via input and output staging chambers.
There is a per se known type of vacuum or reduced pressure method of lamination for adhering a sheet of light sensitive material in film form to a base board for a printed circuit, said base board having a certain degree of non planarity due to circuit patterns and the like formed thereon, as for instance described in Japanese Patent Publication Ser. No. Sho. 59-3740 (1984), which however it is not hereby intended to admit as prior art to the present patent application except to the extent otherwise required by applicable law. In this disclosure, there is described a method of lamination for a light sensitive material in film form by the application of heat and pressure to a base board by the use of a roller in a reduced pressure environment of ambient pressure not more than 200 mmHg. Furthermore, in Japanese Patent Publication Ser. No. Sho. 53-31670 (1978), there is described a device for reduced pressure lamination of such a base board, which has input and output sealing devices, comprising and employing rollers for carrying out the supply of the base board to be laminated and the taking out of the laminated finished product and for providing seals, such as shown in transverse sectional view in FIG. 5 of the accompanying drawings. In that figure, the reference numerals 1 denote parallel and mutually contacting rollers, constructed to have resilient outer surfaces as by being covered with rubber or the like, which rotate in the directions as shown in the figure by the arrows "b", and which form a mutual gas tight pressure seal by being pressed together as well as forming gas tight pressure seals by being pressed against a wall 3 of a reduced pressure chamber on either side of a slot 3a formed in said wall 3, said slot 3a leading to the interior of said reduced pressure chamber (not otherwise shown). In operation, a base board 2 for lamination is fed in the direction indicated by the arrow "a" in the figure through between said rollers 1 and then through the slot 3a into the interior of the reduced pressure chamber 3 which is being maintained at a pressure substantially lower than atmospheric pressure, while still the gas tight pressure seal provided between said rollers 1 is substantially maintained due to the resilience of the material of said rollers 1.
Yet further, in Japanese Patent Laying Open Publication Ser. No. Sho. 57-4194 (1982), there is described a refinement of the above described device for reduced pressure lamination of such a base board, which has similar input and output sealing devices comprising and employing rollers for carrying out the supply of the base board to be liminated and the taking out of the laminated finished product while maintaining seals, and further comprises sealing strip constructions such as shown in transverse sectional view in FIG. 6 of the accompanying drawings, in which figure reference numerals like to reference numerals in FIG. 5 denote like parts and openings and so on. The difference between the FIG. 6 construction and the FIG. 5 construction is that the rollers 1, although they are similarly constructed to have resilient outer surfaces as by being covered with rubber or the like and similarly still form an mutual gas tight pressure seal by being pressed together, are not pressed against the wall 3 of the reduced pressure chamber, but rather relatively small gaps are left between said rollers 1 and said reduced pressure chamber wall 3. For providing gas tight seals, instead, on either side of the slot 3a formed in said wall 3 and leading to the interior of said reduced pressure chamber, outside the rollers 1, there are provided constructions comprising bases 5, to which sealing strips 4 are retained by being fixed by retaining bars 6 and fixing bolts 7. The sealing strips 4 are pressed against the outer sides of the rollers 1 in the trailing direction with regard to the rotation of said rollers 1 in the directions indicated by the arrows "b", and are sucked inwards by the reduced pressure in the laminating chamber (to the left in the figure of the wall 3), so as to form good and effective seals against the outer sides of said rollers 1. Again, in operation, the base board 2 for lamination is fed in the direction indicated by the arrow "a" in the figure through between said rollers 1 and then through the slot 3a into the interior of the reduced pressure chamber 3 which is being maintained at a pressure substantially lower than atmospheric pressure, while still the gas tight pressure seal provided between said rollers 1 is substantially maintained due to the resilience of the material of said rollers 1, as the base board 2 nevertheless passes between said rollers 1.
These general types of methods and devices are nowadays in wide use in industry, and particularly it is accepted that the laminating method and device described in the above cited Japanese Patent Publication Ser. No. Sho. 59-3740 (1984) are effective for implemention.
However, improvements are still desired in reduced pressure methods and devices for carrying out lamination, such as for example lamination of light sensitive material in thin film form to a base board. The present devices are effectively limited to carrying out adhesion and lamination of a thin film material to a base board of thickness 3.5 mm or less, and to use of a vacuum pressure of 700 mmHg (60 Torr). Recently, however, along with developments in the art of multi layer printed circuit boards, there has appeared a requirement for a reduced pressure laminating and adhering method and device capable of handling base boards of thickness 3.5 mm to 10 mm, and capable of employing higher vacuum pressures.